CVE-2026-12816

A flaw was found in Bouncy Castle for Java. This vulnerability allows for Message Authentication Code (MAC) forgery in the IESEngine stream-mode. The issue arises from a length-dependent Key Derivation Function (KDF) split, which an attacker could exploit to bypass integrity checks. This could lead to unauthorized manipulation of data.

This is an Important vulnerability. Bouncy Castle for Java is susceptible to Message Authentication Code (MAC) forgery in IESEngine stream-mode due to a length-dependent Key Derivation Function (KDF) split. An unauthenticated, remote attacker could exploit this flaw to compromise the integrity of data protected by the affected cryptographic operations.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.